The effects of low doses of ranitidine on intragastric acidity in healthy men

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Abstract
Background: H2‐receptor antagonists are becoming widely available as over‐the‐counter medications for the treatment of heartburn and excess gastric acidity.Aim: To determine the effects of single low doses of ranitidine on intragastric acidity.Methods: Intragastric pH was measured for 9 h after lunch in five studies involving 24 healthy male volunteers. Antacid was given to all subjects on day 1. They then received single oral doses of a study drug 45 min after lunch on four separate occasions: placebo and either ranitidine 25 mg, 75 mg or 125 mg were given double‐blind according to a predetermined randomization schedule.Results: During both of the post‐dosing time periods (0–5 h and 5–9 h) there were significant decreases in integrated intragastric acidity for each ranitidine dose compared with placebo (P < 0.0001). There was a significant linear relationship between dose and integrated intragastric acidity with a greater decrease in acidity with increasing ranitidine doses (P < 0.0001). Compared with placebo, time with pH > 3 was significantly greater for ranitidine 75 mg and 125 mg (P < 0.001), but not ranitidine 25 mg. Results with the antacid were similar to placebo.Conclusions: Using low doses of ranitidine (25, 75 or 125 mg) there was a dose‐related decrease in intragastric acidity for 9 h after dosing. A single dose of antacid did not decrease intragastric acidity significantly.